This invention relates generally to devices for extracting water and other liquids from liquid impregnated materials, such as waste, pulp, raw sewage and waste water in general, and more particularly, to such a unit employing an inverted, hyperbolic two-part cone.
The device which is the subject of this invention finds particular use with a waste disposal apparatus or system wherein upon treatment of the waste material, means must be provided for separating the solids and the liquids from within a slurry. This waste disposal system in general, may or may not include a pulper having a tank containing the waste material, fibrous material, garbage and other disposable waste in the presence of a high percentage of water, all being subjected to the disintegrating action of a rotatable impeller having suitable material disintegrating cutters. (see commonly assigned U.S. Pat. Nos. 2,729,146; 3,164,329; 3,584,800; 3,620,460 and 3,885,745.) In apparatus of this type there is associated with the tank discharge, a means for delivering the water-laden material to a liquid extracting device often referred to as a hydra-extractor in which a helical screw is made to undergo rotation within a cylindrical sieve. The hydra-extractor separates the solids from the liquids by withdrawing the liquid from the material received from the pulper or selected disintegrating or mascerating unit. In U.S. Pat. No. 3,394,649, having a common assignee with this application, there is disclosed such a hydra-extractor in which there is a cylindrical screen or hollow cylindrical sieve surrounding the major portion of the screw.
The hydra-extractor must be designed so that it will efficiently separate the liquids and the solids and not overload the screw during the process. Additionally, the back pressure or pressure against which the material moves on the helical screw must be maintained within predetermined limits and the device must be capable of operating almost immediately after shutdown during which period materials within the device can dry and harden and often tend to raise the back pressure.
In the past cones have commonly been composed of brass to minimize corrosiveness. In addition, prior art plug cutters and cones have been composed of an integral material and coupled with the screw shaft, leading to difficulties in installation, replacement, and maintenance.
Prior art hydra-extractors employing V-shaped cones having flat sides have also encountered problems with adhesion of pulp to the cone resulting in drag upon the flow of drying material and increased back pressure.